Slaves Left to Die is a woodcut illustration from the book, The Boy Travellers on the Congo, published in 1888. Accompanying the illustration is a description of why slave owners killed captives while travelling. . .

"Sometimes they left them to die or recover, as best they might, and Dr. Livingstone tells how he saw groups of dying people with slave yokes around their necks, near the road where he travelled. Some of the slave-traders were tender-hearted enough not to take life wantonly, but this was not always the case. Those who looked upon the dreadful traffic purely in the light of business made it a rule to kill every slave who could not keep up with the caravan. They did so not from any special delight in the killing, but becasue it spurred the survivors on to endure the hardships of the march, and never to yield as long as there was power to drag one foot before the other."
Image Credit: Harvard College Library